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.if \n[.g] .mso www.tmac
.TH ykchalresp "1" "Febuary 2011" "yubikey-personalization"
.SH NAME
ykchalresp - Perform challenge-response operation with YubiKey
.SH SYNOPSIS
.B ykchalresp
[\fI-1\fR | \fI-2\fR] [\fI-H\fR] [\fI-Y\fR] [\fI-N\fR] [\fI-x\fR] [\fI-v\fR] [\fI-6\fR] [\fI-8\fR] [\fI-t\fR] [\fI-V\fR] [\fI-h\fR]
.SH DESCRIPTION
.PP
Send a challenge to a YubiKey, and read the response.  The YubiKey can be configured
with two different C/R modes -- the standard one is a 160 bits HMAC-SHA1, and the other
is a YubiKey OTP mimicing mode, meaning two subsequent calls with the same challenge
will result in different responses.
.SH OPTIONS
.TP
\fB\-1\fR
send the challenge to slot 1.  This is the default.
.TP
\fB\-2\fR
send the challenge to slot 2.
.TP
\fB\-H\fR
send a 64 byte HMAC challenge.  This is the default.
.TP
\fB\-Y\fR
send a 6 byte Yubico OTP challenge.
.TP
\fB\-N\fR
non-blocking mode -- abort if the YubiKey is configured to require a key press before
sending the response.
.TP
\fB\-x\fR
challenge is hex encoded.
.TP
\fB\-v\fR
enable verbose mode.
.TP
\fB\-6\fR
output the response in OATH format, 6 digits.
.TP
\fB\-8\fR
output the response in OATH format, 8 digits.
.TP
\fB\-t\fR
use current time as challenge instead of reading challenge from command line (as in default TOTP mode, seconds since 1970-01-01 00:00:00 / 30 encoded as an 8 byte challenge).
.TP
\fB\-V\fR
print tool version and exit.

.SH EXAMPLE
The YubiKey challenge-response operation can be demonstrated using the
\fBNIST PUB 198 A.2\fR test vector.
.P
First, program a YubiKey with the test vector :
.HP
.nf
$ \fBykpersonalize \-2 \-ochal\-resp \-ochal\-hmac \-ohmac\-lt64 \-a 303132333435363738393a3b3c3d3e3f40414243\fR
 ...
Commit? (y/n) [n]: y
$
.fi
.HP
Now, send the NIST test challenge to the YubiKey and verify the result matches the
expected :
.HP
.nf
$ \fBykchalresp \-2 'Sample #2'\fR
0922d3405faa3d194f82a45830737d5cc6c75d24
$
.fi

.SH BUGS
Report ykchalresp bugs in
.URL "https://github.com/Yubico/yubikey-personalization/issues" "the issue tracker"
.SH "SEE ALSO"
The
.URL "https://developers.yubico.com/yubikey-personalization/" "ykpersonalize home page"
.PP
YubiKeys can be obtained from
.URL "http://www.yubico.com/" "Yubico" "."